Israeli Prime Minister Benjamin Netanyahu’s rejection of a potential agreement on Iran’s nuclear program, which he denounced as a “very bad deal,” threatens to ignite the most serious U.S.-Israel dispute in years.

His public criticism follows a series of meetings on the topic with U.S. Secretary of State John Kerry, who flew to Geneva today to join talks with Iranian Foreign Minister Mohammad Javad Zarif. They’re seeking to nail down the first step in an accord that would relieve some sanctions against Iran if it curtails certain nuclear activities.

The clash over Iran negotiations follows an effort by PresidentBarack Obama to reassure Netanyahu of his support for Israel, including a trip there in March, after a series of disputes. Kerry’s talks with Netanyahu have sought to avoid a blanket rejection of initial moves toward a nuclear pact, which could fuel opponents in the U.S. Congress pressing to toughen sanctions.

Netanyahu told reporters today that Israel “utterly rejects” and “is not obliged by” an agreement that world powers and Iran are trying to put together. He spoke before a morning meeting with Kerry, who stopped in Tel Aviv from Jordan en route to Geneva for the nuclear talks.

“I understand that the Iranians are walking around very satisfied in Geneva, as well they should be, because they got everything and paid nothing,” Netanyahu said. “Iran got the deal of the century and the international community got a bad deal. This is a very bad deal.” see more